While I don't have any hard ridership numbers to support this, but office space has been on an incline in Downtown Bklyn according to this 2017 report: https://www.osc.state.ny.us/osdc/rpt10-2017.pdf. It's long so I'll summarize some quotes.
In addition, Buswick/Willyb have become inhabited by lots of hip white transplants who are working in hip startup companies, who in turn tend to be attracted to Brooklyn. So I'll believe that a large amount of people transferring at Canal to the downtown .